Clin Orthop Surg.  2017 Jun;9(2):218-222. 10.4055/cios.2017.9.2.218.

Acromion Index in Korean Population and Its Relationship with Rotator Cuff Tears

  • 1Department of Orthopaedic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.


Among the many causes of rotator cuff tears, scapular morphology is associated with the accelerating degenerative process of the rotator cuff. Acromion index (AI) was previously introduced and compared in two populations.
We enrolled 100 Korean patients diagnosed with full-thickness rotator cuff tears by magnetic resonance imaging and intraoperative arthroscopic findings between January and December 2013. Another 100 Korean patients with an intact rotator cuff tendon identified on magnetic resonance imaging and other shoulder diseases, such as frozen shoulder and instability, were enrolled as controls. We retrospectively compared these 100 rotator cuff tear patients (mean age, 63 years) and 100 controls (mean age, 51 years) in this study. Two independent orthopedic surgeons assessed the AI on radiographs. We performed an interobserver reliability test of the AI assessment, and then compared the AI between two groups.
The measurement of the AI showed excellent reliability (intraclass correlation coefficient, 0.82). The mean AI in the rotator cuff tear group was 0.68 and it was significantly different between groups (p<0.001, 95% confidence interval). The AI was not related to tear size.
Our study showed that the AI was an effective predictive factor for rotator cuff tears in a Korean population.


Shoulder; Acromion; Rotator cuff injury; Prognosis

MeSH Terms

*Acromion/anatomy & histology/diagnostic imaging
Aged, 80 and over
Asian Continental Ancestry Group/*statistics & numerical data
Magnetic Resonance Imaging
Middle Aged
ROC Curve
Republic of Korea/epidemiology
Retrospective Studies
*Rotator Cuff Injuries/diagnostic imaging/epidemiology


  • Fig. 1 Acrominon index (AI). (A) AI was defined as the ratio of the distance from the glenoid to the lateral margin of the acromion (GA) divided by the distance from the glenoid rim to the lateral aspect of the humeral head (GH). (B) Anteroposterior radiographic view of the right shoulder: calculation of AI was done according to the method described in Fig. 1A.

  • Fig. 2 Comparison of acromion index (AI) on true anteroposterior (AP) radiographs: the AI was higher in the shoulder with a rotator cuff tear (A) than in the shoulder with an intact rotator cuff (B).

  • Fig. 3 Receiver operating characteristic curve for the acromion index in blue line. The reference line is indicated in black line.


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